Influence of radiative heat transfer on variation of cell voltage within a stack

In this study, a numerical investigation of cell-to-cell voltage variation by considering the impact of flow distribution and heat transfer on a stack of cells has been performed. A SOFC stack model has been previously developed to study the influence of flow distribution on stack performance (Burt, et al., 2003). In the present study the heat transfer model has been expanded to include the influence of radiative heat transfer between the PEN (positive electrode, electrolyte, negative electrode) and the neighboring separator plates. Variations in cell voltage are attributed to asymmetries in stack geometry and nonuniformity in flow rates. Simulations were done in a parallel computing environment with each cell computed in a separate (CPU) process. This natural decomposition of the fuel cell stack reduced the number of communicated variables thereby improving computational performance. The parallelization scheme implemented utilized a message passing interface (MPI) protocol where cell-to-cell communication is achieved via exchange of temperature and thermal fluxes between neighboring cells. Inclusion of radiative heat transfer resulted in more uniform temperature and voltage distribution for cases of uniform flow distribution. Non-uniform flow distribution still resulted in significant cell-to-cell voltage variations.